Light signal



April 30, 1946- M. R. DOUGLASS LIGHT SIGNAL Filed Jan. 29, 1942INVENTOH. Nyg lfiaglarr. I HmAr romvEY.

Patented Apr. 30, 1946 LIGHT SIGNAL Myrl R. Douglass, Edgewood, Pa.,a'ssignor to The Union Switch & Signal Company, Swissvale, Pa., acorporation of Pennsylvania Application January 29, 1942, Serial No.428,734

7 Claims.

My invention relates to light signals, and particularly to light signalswhich are capable of selectively projecting a plurality of beams oflight of different colors from a single light source.

More particularly, my present invention relates to Searchlight signalsemploying a spectacle arm provided with red, yellow and green colorfilters adapted to be selectively interposed in the signal beam to causethe signal to display stop, approach and clear indications, and has foran object the provision of a novel three-position operating mechanismfor the spectacle arm employing two tractive type electromagnets, andcapable of operating the spectacle arm from its approach to its clearposition or vice versa without passing through the stop position.

Another object of m invention is the provision of novel means forcontrolling the electromagnets to permit the signal to be operated froma polarized line or track circuit.

Accordin to m invention, a vane carrying the color filters is biased bya counterweight to one extreme position in which the red filter isdisposed in the path of the light beam, and is arranged to be moved fromthis position to the approach and clear positions by means of an armoperatively connected with the vane. This arm cooperates with a firstpivoted lever the free end of which overlies a second pivoted lever. Thelevers are operatively connected with lever cams operated by rollerssecured to the armatures of two tractive type electromagnet's, The partsare so proportioned that when both electromagnets are deenergized, thespectacle arm is permitted to move to its stop position due to itscounterweight bias, when one electromagnet is energized and the otherdeenergized, the spectacle arm will be moved to its approach position,and when both electromagnets are energized, the spectacle arm will bemoved to its clear position.

The two electromagnets are adapted to be energized from a polarizedcircuit, and the one electromagnet is supplied with energy from thiscircuit through means which causes the current to always flow in thesame direction through said one electromagnet, The other electromagnetis energized over a contact which is closed only when said oneelectromagnet is energized, and over other contacts which are closedwhen and only when a polar relay is energized b current of a selectedpolarity, The polar relay is energized from the polarized circuit.

Other objects and characteristic features of my invention will becomeapparent as the description proceeds.

fit

I shall describe one form of light signal embodying m invention and onecontrol arrangement therefor, and shall then point out the novelfeatures thereof in claims.

In the accompanyin'g'drawing, Fig. 1 is an isometric view showing oneform of light signal embodying my invention. 'Fig. 2'is a view showing acontrol arrangement for the signal shown in Fig- Similar referencecharacters refer to similar parts in both views,

Referring first to Fig. Lthe signal in the form here shown comprises asuitable optical assembly consisting of an electric lamp 1, a reflector2, and an objective lens 3 so disposed that the reflector 2 will collecta large percentage of the rays of light emitted by the lamp l and willcause them to converge at a focal point '4, and then diverge in order tocover the surface of the objective lens 3 as indicated by the dot anddash lines 5. The various parts of the optical assembly are all ofwell-known construction, and are illustrated in the drawing indiagrammatic form in order to simplify the disclosure,

Associated with the optical assembly is a spectacle arm 6, the upper endof which is provided with three differently colored screens or filtersR, Y and G. The spectacle arm is secured at its lower end to a pivotedshaft 1, and is capable of being moved from a stop position in which thefilter R is interposed in the path of the light rays adjacent the focalpoint 4, to an approach position in which the filter Y is interposed inthe path of the light rays adjacent the focal point 4, and a clearposition in which the filter G is interposed in the path of the lightrays adjacent the focal point 4. It will be apparent that when one ofthe filters is located in the path'of the light rays, the light rayswill pass through the filter so that only the light rays of the colorwhich are not filtered out can emerge from the signal. Since the filtersare differently colored, it follows that the signal is capable ofdisplaying three different aspects depending upon which of the colorfilters is disposed at the focal point 4.

In the practical application of a light signal embodying my invention torailway signaling, the spectacle arm is biased by its own weight, and bythe weight of a counterweight 8 which is secured to the shaft 1, to thestop position, and the filter R is colored red so that when thespectacle arm occupies its stop position, the projected beam will be redindicating stop. Furthermore, the filter Y is colored yellow and thefilter G is colored green so that when the arm occupies its approachposition, the signal will be yellow, indicating approach, and when thearm occupies its clear position, the beam will be green, indicatingclear.

The spectacle arm is arranged to be moved from stop to its approach andclear positions by means of three-position operating mechanism embodyingmy present invention, which mechanism I shall now described. As hereshown, this mechanism comprises two electromagnets H and D which I shallterm for convenience home and distant electromagnets. The twoelectromagnets H and D are of well-known construction, and eachcomprises a pair of magnetizable pole pieces I and I I connectedtogether at one end by a magetizable backstrap I2, and cooperating attheir opposite ends with a tractive type armature I 3 pivotally mountedat M for swinging movement toward and away from the pole pieces I0 andII. Each backstrap I2 is provided with an energizing winding I5.

Associated with the distant magnet D is an L-shaped permanent magnet I6which is secured at its upper end to the pole piece II, and the lowerend of which extends underneath the associated armature I3 opposite thepole face of its pole piece II in such manner that when the armature isswung away from the pole pieces I6 and II, it will be swung toward itspermanent magnet and vice versa.

Assuming that the lower end of the permanent magnet I6 is a north poleand the upper end a south pole, as indicated by the letters N and S inthe drawing, when the winding I5 of electromagnet D is deenergized, theassociated armature I3 will drop under the influence of gravity to theposition shown, and under these conditions a part of the flux from thepermanent magnet will pass lengthwise through the armature and willexert a torque on the armature which assists the pull of gravity inholding the armature in its lowermost position. When, however, thewinding I5 is energized in such manner that the pole piece II becomes asouth pole and the pole piece Ii) a north pole, the permanent magnet andthe electromagnet fluxes will buck each other in the armature I3, and asthe electromagnet flux builds up in the armature, a point will bereached at which the upward pull exerted on the armature by this fluxwill exceed the downward pull due to the permanent magnet flux and theforce of gravity. When this happens, the armature I3 will swing towardthe pole pieces Ill and II to its upper or attracted position.

If, when the armature l3 of electromagnet D occupies its releasedposition, the Winding I5 is energized in such a direction that the polepiece II becomes a north pole and the pole piece It] becomes a southpole, the flux due to the electromagnet and the permanent magnet willthen thread the armature I3 in the same direction, and under theseconditions, the armature I3 will remain in the position shown eventhough the energization of the winding is increased to many times itsnormal value.

If the polarity of the permanent magnet I6 is reversed from that shownin the drawing, the electromagnet D will operate in a manner similar tothat just described except for the fact that the polarity of the currentwhich must be supplied to the winding I5 to cause the armature 13 topick up will be reversed.

The home magnet H operates in the usual and well-known manner. That isto say, its armature l3 will be picked up or released according as itsenergizing winding I5 is energized or deenergized.

Attached to the armatures I3 of the home and distant electromagnets Hand D adjacent their free ends are laterally projecting pins 20 and 2Iwhich align axially when the armatures are both picked up or bothreleased, and mounted on these pins are rollers 22 and 23. These rollerscooperate, respectively, with lever cams 24 and 25 fixed to axiallyaligned pivoted shafts 26 and 21. Also fixed to the shaft 2'; is an arm28, the free end 28a of which is offset laterally and overlies anupwardly offset portion 29a formed on the free end of an arm 29 fixed tothe shaft 26. A forwardly projecting pin 30 is secured to the offset end28a of the arm 28, and this pin cooperates with the underside of adownwardly inclined radially extending arm 9 fixed to the shaft I whichsupports the spectacle arm 6.

The arm 29 due to its weight acts to maintain the cam surface 22a of thecam arm 24 in constant engagement with the roller 22, and it will beapparent, therefore, that the arm 29 will be moved to an upper position,or will drop by gravity to a lowermost position according as armature I3of electromagnet H is picked up or released. The lever cam 25 isprovided at its lower end with a rounded cam surface 25a which mergesinto an inclined cam surface 25b. The rounded cam surface 25a defines anarc whose center of curvature coincides with the axis of rotation of theshaft 2?, and whose radius of curvature is just slightly less than thedistance from the axis of rotation of the shaft 21 to the nearest pointon the roller 23 when the armature I3 oi electromagnet D is released. Itwill be seen, therefore, that when the armature I3 of electromagnet D isreleased, both cam surfaces 25a and 25b of lever cam 25 will remain outof engagement with roller 23, and that under these conditions arm 28will follow the movements of arm 29. The length of cam surface 25a issuch, and the parts are so proportioned that this cam surface willoverlie roller 23, and will act as a mechanical lock to prevent armatureI3 of electromagnet D from picking up, except when arm 28 is movedupwardly by arm 29 to the position corresponding to the upper positionof arm 29, which position of arm 23 I shall term its intermediate"position. The parts are further so proportioned that if electromagnet Dbecomes energized when arm 28 has been moved to its intermediateposition, the roller 23 will cooperate with the cam surface 25b to movethe arm 28 to an upper posi-- tion. The pin 33 carried by arm 28cooperates with the arm 9 secured to shaft 1 in such manner that thespectacle arm will be free to move due to its bias to its stop positionwhen the arm 28 occupies its lowermost position, but that when this armis moved to its intermediate position, the spectacle arm will be movedto its approach position, and that, when this arm is moved to its upperposition, the spectacle arm will then be moved to its clear position. Itwill be seen, therefore, that when both electromagnets are deenergized,the spectacle arm will be held in its stop position due to its gravitybias, when the electromagnet H is energized and the electromagnet D isdeenergized, the spectacle arm will be moved to its approach position,and when the electromagnets H and D are both energized, the spectaclearm will be moved to its clear position.

It will be understood that in actual practice the armatures l3 of theelectromagnets H and D game 3 will each control contacts not shown inthe usual and well-known manner. One of these contacts 33 which iscontrolled by the home electromagnet H is shown diagrammatically in Fig.2 as will appear hereinafter. 7

Referring now to Fig. 2, I have here shown a wiring arrangement for thesignal shown in Fig. l to enable it to be controlled over a polarizedcontrol circuit. As here illustrated, the polarized control circuitcomprises two conductors 3i and 32 connected to a battery C over a polechanger PC which may either be operated manually or may comprise thecontacts of a relay. The winding of the home electromagnet H isconnected with the conductors 3| and 32 through suitable means, hereshown as a full wave rectifier R, which means will cause it to ,besupplied with current of the same polarity whenever the line wires aresupplied with current of either polarity.

The home magnet is preferably made slow releasing by winding theenergizihg winding I5 on a copper sleeve, in accordance with well-knownpractice, and this fact coupled with the fact that the. asymmetric unitsof the rectifier R provide a low resistance shunt path around thewinding for currents induced by the decaying flux in the core of themagnet, cause the home magnet to retain its armature closed while thepolarity of the line circuit is being reversed under normal the linewires 3! and 32. The polar relay PR is so constructed that it will closeits reverse contacts 3434b and 35-35b to complete the circuit forelectromagnet D when and only when the line wires are supplied withcurrent of the polarity to which the electromagnet D will respond, whichpolarity I shall term for convenience reverse polarity.

Associated with relay PR is a load balancing resistor LBR which has thesame resistance as the winding of electromagnet D, and which isconnected with the line wires 3! and 32 over norinal contacts 34-3411and 35-35a of electromagnet PR to cause the line to have the same loadwhen the distant magnet is deenergized that it has when this magnet isenergized.

With the circuit arranged in this manner it will be apparent that whenthe line wires are deenergized, the home and distant magnets will bothbe deenergized and the signal will then display its stop aspect. When,however, the line circuit is supplied with current of normal polarity,the home magnet will become energized and the distant magnet will remaindeenergized to cause the signal to display its caution aspect, and whenthe line circuit is supplied with current of reverse polarity, both thehome and distant magnets will become energized to cause the signal todisplay its clear aspect.

It should be particularly pointed out that with the control circuitconstructed in the manner just described electromagnet D is preventedfrom picking up except when the line wires are supplied with current ofthe proper polarity, for two reasons. In the first place, the contacts3434b and 35-351) of relay PR act to cut off energy from theelectromagnet D unless the line circuit is supplied with current ofreverse polarity, and in the second place, magnet I6 is effective toprevent verse contacts 34-342) and 35'b of a polar relay PR which latteris connected directly with armature l3 of electromagnet D from pickingup except when winding 15 is supplied with current of reverse polarity.

It should also be particularly pointed out that contact 33 of the homemagnet H cuts off energy from the distant magnet D unless the homemagnet is pieked up. Moreover, this contact offers a delay factor toallow the home magnet H to pick up ahead of the distant magnet D in theevent reverse energy is applied to the line wires 3| and 32 withoutnormal energy having first been applied to these line wires. This delayfactor permits the relay PR to assume its normal position when the homemagnet only becomes picked up should the entire unit have previouslybeen deenergized with the polar relay PR in the reverse position, thuseliminating the possibility of momentary energy being supplied to thedistant magnet D under conditions when it should be deenergized. Themagnetic bias provided by the permanent magnet l6 for the armature l3 ofelectromagnet D is probably sufiicient to take care of this condition,but contact 33 offers an additional factor of safety.

The wiring arrangement just described provides adequate safety featuresand satisfactorily meets all safety standards. unit become deenergized,the signal will immediately assume its most restrictive aspect. If thearmature of the home electromagnet should be dropped to its releasedposition for any reason, the distant electromagnet is automaticallydeenergized. If any leg of rectifier R breaks down, the worst conditionthat can happen is a short circuit of the home electromagnet H whichwill deenergize the distant electromagnet due to the opening of thecontact 33 of the home electromagnet, and the signal Will thereforedisplay its stop aspect. The signal can be operated from a polarizedline or track relay without intermediate relays. Cont-acts can be addedwhich will permit control of other functions and to permit pole changingof the circuits for the signal next in rear.

Although I have herein shown and described only one form of light signalembodying my invention, it is understood that various changes andmodifications may be made therein within the scope of the appendedclaims without departing from the spirit and scope of my invention.

' Having thus described my invention, What I claim is:

1. A three position motor device comprising a member biased to a firstposition and movable to second and third positions, an arm secured tosaid member, two electromagnets each provided with an armature, twopivoted levers one operatively connected with each armature, meansresponsive to movement of the one lever for at times causing movement ofthe other lever, and a pin secured to the free end of said other leverand cooperating with said arm for moving said member from its first toits second position when the one lever is actuated by energization ofthe associated electromagnet and from its second to its third positionwhen the other lever is actuated by the associated electromagnet.

2. A three position motor device comprising a pivoted shaft biased to afirst position and rotatable from its first position to second and thirdpositions, an arm operatively connected with said shaft, twoelectromagnets each provided with a pivoted armature, a first pivotedlever the free end of which overlies a second pivoted lever, a pinsecured to the free end of said first pivoted lever Should the operatingand cooperating with said arm for moving said shaft, means controlled bythe armature of one of said electromagnets for actuating said firstpivoted lever, and means controlled by the other electromagnet foractuating said second pivoted lever, the parts being so proportionedthat when both electromagnets are deenergized said shaft is permitted tomove to its first position due to its bias, when said otherelectromagnet is energized and said one electromagnet deenergized saidshaft is moved to its second position, and when both electromagnets areenergized said shaft is moved to its third position.

3. An electroresponsive device comprising two laterally spacedelectromagnets each provided with a pivoted armature, a roller carriedby each armature, two axially aligned shafts, two cam arms secured tosaid two shafts respectively and one cooperating with each of saidrollers, third and fourth arms secured to said two shafts respectively,said third arm being provided with a portion which overlies said fourtharm, a pin secured to said third arm, and a pivoted member biased to afirst position and movable by means of said pin to second and thirdpositions.

4. An electroresponsive device comprising two spaced electromagnets eachcontrolling a pivoted armature, the one said electromagnet beingprovided with means cooperating with the associated armature to preventthe armature from picking up except when said one electromagnet isenergized by current of a particular polarity, two pivoted arms the freeend of one of which overlies the free end of the other arm, a pivotedmember operatively associated with both said arms, means operativelyconnecting said other arm with the armature controlled by said otherelectromagnet, and means operatively connecting said one arm with thearmature controlled by said one electromagnet in such manner that saidlast mentioned armature is prevented from picking up unless said otherarm is first actuated by its associated armature.

5. An electroresponsive device comprising a first and secondelectromagnet controlling first and second pivoted armatures, first andsecond pins attached to said first and second armatures and disposed toalign axially when both armatures are picked up or released, first andsecond rollers mounted on said first and second pins,

respectively, first and second axially aligned pivoted shafts, first andsecond cam arms secured to said first and second shafts respectively andcooperating with said first and second rollers, respectively, saidsecond cam being formed with an arcuate cam surface having a center ofcurva ture which coincides with the axis of said second shaft and havinga radius of curvature slightly less than the distance from the axis ofsaid second shaft to the nearest point on said second roller when saidsecond armature is released, third and fourth arms secured to said firstand second shafts, respectively, said fourth arm being provided at itsfree end with a portion which overlies the free end of said third arm,and a movable member operable to a plurality of positions by said thirdand fourth arms.

6. An electroresponsive device comprising a first and secondelectromagnet controlling first and second pivoted armatures, first andsecond pins attached to said first and second armatures and disposed toalign axially when both armatures are picked up or released, first andsecond rollers mounted on said first and second pins, respectively,first and second axially aligned pivoted shafts, first and second camarms secured to said first and second shafts respectively andcooperating with said first and second rollers, respectively, saidsecond cam arm being formed with an arcuate cam surface having a centerof curvature which coincides with the axis of said second shaft andhaving a radius of curvatures slightly less than the distance from theaxis of said second shaft to the nearest point on said second rollerwhen said second armature is released, third and fourth arms secured tosaid first and second shafts respectively, said fourth arm beingprovided at its free end with a portion which overlies the free end ofsaid third arm, and the parts being so proportioned that said arcuatecam surface will cooperate with said second roller to prevent saidsecond armature from picking up until said first armature has firstpicked up to move said third arm from a lower to an upper position andthrough the movement of said third arm said fourth arm from a lower toan intermediate position, said fourth arm being movable from itsintermediate to an upper position through the cooperation of said secondroller with said second cam arm in response to the picking up of saidsecond armature, and a movable member operatively connected with saidfourth arm.

7. An electrorespcnsive device comprising a first and secondelectromagnet controlling first and second pivoted armatures, first andsecond pins attached to said first and second armatures and disposed toalign axially when both armatures are picked up or released, first andsecond rollers mounted on said first and second pins, respectively,first and second axially aligned pivoted shafts, first and second camarms secured to said first and second shafts respectively andcooperating with said first and second rollers, respectively, saidsecond cam arm being formed with an arcuate cam surface having a centerof curvature which coincides with the axis of said second shaft andhaving a radius of curvature slightly less than the distance from theaxis of said second shaft to the nearest point on said second rollerwhen said second armature is released, third and fourth arms secured tosaid first and second shafts respectively, said fourth arm beingprovided at its free end with a portion which overlies the free end ofsaid third arm, and the parts being so proportioned that said arcuatecam surface will cooperate with said second roller to prevent saidsecond armature from picking up until said first armature has firstpicked up to move said third arm from a lower to an upper position andthrough the movement of said third arm said fourth arm from a lower toan intermediate position, said fourth arm being movable from itsintermediate to an upper position through the cooperation of said secondroller with said second cam arm in response to the picking up of saidsecond armature, a pivoted member biased to a first position and movableto second and third positions, and means opcratively connecting saidfourth arm with said pivoted member for moving said pivoted member fromits first to its second position in response to movement of said fourtharm from its lower to its intermediate position and from its second toits third position in response to movement of said fourth arm from itsintermediate to its upper position.

MYRL R. DOUGLASS.

